Field of the Invention
The present invention relates to the recovery of a section of casing pipe from a well that has been cased with the casing pipe. The present invention relates to a method and a tool for the use in the recovery of a section of casing to prepare the well for plugging and abandoning the well or for recovering a slot in a template on a seafloor used for drilling multiple wells for recovering hydrocarbons.
Background of the Related Art
Earthen wells are drilled into the earth's crust to provide access to geologic formations bearing hydrocarbons. Tubulars can be run into the drilled well to provide a fluid conduit for the recovery to the earth's surface of minerals such as, for example, oil or gas, from subsurface geologic formations. Earthen wells may also be drilled to provide a fluid conduit for disposal of waste fluids or for the maintenance of pressure in a mineral bearing reservoir by injection of fluids through the well and into the reservoir.
After a well is drilled, it is generally cased with a string of casing, which are tubular joints joined at the ends to provide a casing string. The casing string is generally cemented in place within the drilled well. After the well has served its intended purpose, it is usually plugged and abandoned. Plugging and abandonment involves the removal from the well of at least a section of the casing string, followed by the plugging of the well using a cement plug. This type of plugging and abandonment prevents unwanted cross-flow between geologic formations and zones that are penetrated by the well.
In some offshore fields, subsea templates are constructed on the seafloor to provide a plurality of slots from which wells can be drilled to access a subsurface geologic formation bearing hydrocarbons. A slot in the template may become inactive if the well has structural problems or if the geologic formation in which the well is perforated becomes watered out or otherwise unproductive. It is advantageous to recover the slot for use in drilling a new well to a different geologic formation or to a different portion of the same geologic formation.
An effective placement of a cement plug to abandon a well in a manner that prevents unwanted cross-flow of penetrated geologic formations requires the removal of a section of casing from the well. A volume of a cement slurry can then be pumped into the portion of the well from which the casing is removed and pressurized to promote cement bonding as the cement slurry sets. Some conventional methods and tools use a marine swivel having a large mass for being supported on a wellhead or on a slot of a seafloor template. The marine swivel includes a mandrel extending into the well from the marine swivel that rotates a cutting tool to cut the casing. The mandrel is rotated by rotation of a tubular string extended through a riser from a platform or rig. Once the cutting tool successfully cuts the casing at a targeted location, the marine swivel is removed and the cutting tool is retrieved. A gripping tool coupled to a tubular string is then run into the well and deployed to grip a section of the casing above the location of the cut. Withdrawal of the tubular string retrieves the gripping tool and the gripped section of casing from the well.
A shortcoming of the conventional methods and tools used for removing a section of casing from a well for plug and abandonment or slot recovery arises from the need to withdraw the cutting tool from the well so that a casing gripping tool can be run into the well to grip and retrieve the section of casing. This process, which includes at least two trips with two different tools on the tubular string, requires a large amount of rig time.
Another shortcoming of conventional methods and apparatus used for removing a section of casing from a well arises from the inability to easily and conveniently reset the location of the cutting tool. The marine swivel is supported on the wellhead or seafloor template, and the distance between the marine swivel and the cutting tool supported from the marine swivel is not variable or adjustable. In the event that the cutting tool gets hung up or jammed, or if the first attempt to cut the casing is unsuccessful, the position of the cutting tool in the well casing cannot be adjusted.
Some conventional casing gripping tools can be positioned within the targeted section of casing to be removed from the wellbore and then deployed to grip the casing by rotation of the tubular string to which the tool is threadably connected. These tools cannot allow for rotation of a cutting element connected distally to the tool because rotation of the tubular string is used for deploying and retracting the gripping elements of the tool. These conventional casing gripping tools require two trips into the well, the first trip to cut the casing and the second trip to grip and remove the cut section of casing.
Embodiments of the gripping tool and method of the present invention overcome these and other shortcomings of existing methods and tools.